Nutritional Intervention to Prevent Diabetes

There are two possible entry pathways for study participants. The first pathway is the entry point for pregnant mothers in their third trimester (24 weeks gestational age) whose babies may be at higher risk for T1D based on family history. At birth, or soon after, their babies will be tested for HLA type (to look for the specific gene which confers a higher risk of developing T1D). If the HLA typing shows that the baby is at higher risk for T1D and no protective genes are present, the baby will then continue in the study. The second pathway is the entry point for babies whose mothers were not enrolled during pregnancy. These babies will also be tested for HLA type. Their eligibility will be based on the presence of higher risk genes or the presence of a multiplex family history. This screening process may take place up until the baby is 5 months old. Eligible participants (pregnant women or infants) will be randomized to one of the two study groups: DHA (docosahexaenoic acid) study substance (this is the intervention) or control study substance (this is the placebo). The DHA (docosahexaenoic acid) to be used in this trial is produced from algae, not from fish oil, so there is no risk of mercury or pesticide contamination. Pregnant and nursing mothers who are assigned to the control group will receive study capsules containing a vegetable oil and no DHA (docosahexaenoic acid) . Pregnant and nursing mothers who are assigned to the experimental group will receive study capsules containing DHA (docosahexaenoic acid) . During pregnancy and while breastfeeding, infants will receive the study substance indirectly through their mother (either the placenta or breastmilk). Infants who are either partially or exclusively formula feeding will receive study substance more directly through the study formula. The control group will receive study formula containing the typical amount of DHA that can be found in some infant formulas, while infants in the experimental group will receive study formula containing a larger amount of DHA (docosahexaenoic acid) than typically found in some infant formulas. By six to twelve months of age, all infants will get study supplement added to solid foods. All mothers will have contact with the study site every 3 months. Nursing mothers will provide samples of breast milk for fatty acids analysis at these visits. Infants will need to come to follow-up study visits every 6 months. At each of these visits, the infant will have a limited physical exam and blood drawn from a vein to monitor immune activity, levels of fatty acid and vitamin D, and to check for diabetes-related autoantibodies. Infants/children cannot continue in the study if they: (1) develop two positive autoantibodies, present at two consecutive visits, or (2) develop T1D. All follow-up study visits will continue for 1-2 years, and possibly an additional 2 years if a full-scale study is initiated.